<?php
/**
 * Zend Framework
 *
 * LICENSE
 *
 * This source file is subject to the new BSD license that is bundled
 * with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://framework.zend.com/license/new-bsd
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@zend.com so we can send you a copy immediately.
 *
 * @category   Zend
 * @package    Zend_Pdf
 * @copyright  Copyright (c) 2005-2009 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 * @version    $Id: AsciiHex.php 18993 2009-11-15 17:09:16Z alexander $
 */


/** Zend_Pdf_Filter_Interface */
require_once 'Zend/Pdf/Filter/Interface.php';

/**
 * AsciiHex stream filter
 *
 * @package    Zend_Pdf
 * @copyright  Copyright (c) 2005-2009 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 */
class Zend_Pdf_Filter_AsciiHex implements Zend_Pdf_Filter_Interface
{
	/**
	 * Encode data
	 *
	 * @param string $data
	 * @param array $params
	 * @return string
	 * @throws Zend_Pdf_Exception
	 */
	public static function encode($data, $params = null)
	{
		return bin2hex($data) . '>';
	}

	/**
	 * Decode data
	 *
	 * @param string $data
	 * @param array $params
	 * @return string
	 * @throws Zend_Pdf_Exception
	 */
	public static function decode($data, $params = null)
	{
		$output  = '';
		$oddCode = true;
		$commentMode = false;

		for ($count = 0; $count < strlen($data)  &&  $data[$count] != '>'; $count++) {
			$charCode = ord($data[$count]);

			if ($commentMode) {
				if ($charCode == 0x0A  || $charCode == 0x0D ) {
					$commentMode = false;
				}

				continue;
			}

			switch ($charCode) {
				//Skip white space
				case 0x00: // null character
					// fall through to next case
				case 0x09: // Tab
					// fall through to next case
				case 0x0A: // Line feed
					// fall through to next case
				case 0x0C: // Form Feed
					// fall through to next case
				case 0x0D: // Carriage return
					// fall through to next case
				case 0x20: // Space
					// Do nothing
					break;

				case 0x25: // '%'
					// Switch to comment mode
					$commentMode = true;
					break;

				default:
					if ($charCode >= 0x30 /*'0'*/ && $charCode <= 0x39 /*'9'*/) {
						$code = $charCode - 0x30;
					} else if ($charCode >= 0x41 /*'A'*/ && $charCode <= 0x46 /*'F'*/) {
						$code = $charCode - 0x37/*0x41 - 0x0A*/;
					} else if ($charCode >= 0x61 /*'a'*/ && $charCode <= 0x66 /*'f'*/) {
						$code = $charCode - 0x57/*0x61 - 0x0A*/;
					} else {
						require_once 'Zend/Pdf/Exception.php';
						throw new Zend_Pdf_Exception('Wrong character in a encoded stream');
					}

					if ($oddCode) {
						// Odd pass. Store hex digit for next pass
						// Scope of $hexCodeHigh variable is whole function
						$hexCodeHigh = $code;
					} else {
						// Even pass.
						// Add decoded character to the output
						// ($hexCodeHigh is stored in previous pass)
						$output .= chr($hexCodeHigh*16 + $code);
					}
					$oddCode = !$oddCode;

					break;
			}
		}

		/* Check that stream is terminated by End Of Data marker */
		if ($data[$count] != '>') {
			require_once 'Zend/Pdf/Exception.php';
			throw new Zend_Pdf_Exception('Wrong encoded stream End Of Data marker.');
		}

		/* Last '0' character is omitted */
		if (!$oddCode) {
			$output .= chr($hexCodeHigh*16);
		}

		return $output;
	}
}
